Preparation method of strong-oxidation-resistance fermented wiredrawing soybean milk based on biological enzymolysis and plant polysaccharide modification

Abstract

The invention discloses a preparation method of high-oxidation-resistance fermented wiredrawing soybean milk based on biological enzymolysis and plant polysaccharide modification, and belongs to the technical field of food fermentation. In order to effectively improve the wiredrawing characteristic, the sensory characteristic and the nutritional value of the fermented soybean milk, the invention provides the preparation method of the strong-oxidation-resistance fermented wiredrawing soybean milk based on cooperation of biological enzymolysis and plant polysaccharide modification, and favorable conditions are created for actual production of the fermented soybean milk. The main process comprises the following steps: (1) selecting soybeans, crushing, performing pulping pretreatment, and centrifuging after enzymolysis; (2) mixing 7S soybean protein with the hydrolysate, and carrying out secondary enzymolysis; (3) primarily preparing a mixed solution after sterilization; (4) adding lycium barbarum polysaccharide, homogenizing, sterilizing and cooling; and (5) sterilizing and fermenting to obtain a finished product. According to the production process disclosed by the invention, the nutritional value, the sensory characteristic and the wire drawing characteristic of the fermented soybean milk are improved, and a solid foundation is laid for large-scale production and commercial application of the fermented soybean milk, so that richer economic benefits are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of food fermentation, and in particular relates to a method for preparing fermented drawn soybean milk with strong antioxidant properties based on biological enzymatic hydrolysis and coordinated plant polysaccharide modification. Background Art

[0002] Wire-drawn fermented yogurt is yogurt fermented by specific strains of bacteria. It is rich in active lactic acid bacteria, which can help maintain the balance of intestinal flora and inhibit the growth of harmful bacteria. It can improve the body's immunity and regulate the immune system. Nowadays, plant-based products are popular, and wire-drawn fermented soy milk stands out. On the one hand, it effectively improves the beany smell of traditional soy milk and optimizes the flavor experience. On the other hand, it has the advantages of enhancing antioxidant properties and improving texture characteristics, which significantly improves product quality and nutritional value.

[0003] In the background technology of the present invention, it is related to a specific bacterial strain combination, i.e. thermophilic streptococcus, bifidobacterium lactis, lactobacillus acidophilus and plant lactobacillus. It is found through research that the optimal ratio of the four bacterial strains is 1:1.25:1:1.5. These four microbial strains, under the synergistic effect of conditions such as specific culture matrix, culture temperature, pH value and culture time, can undergo joint metabolic behavior and produce a large amount of extracellular polysaccharides. This characteristic has significant application value in the industrial production field of fermented soy milk, can provide technical support for the actual production process of fermented soy milk, help optimize production technology, improve product quality stability, promote the scale and industrial development of the fermented soy milk industry, and then create considerable economic benefits. Summary of the invention

[0004] The purpose of the present invention is to effectively improve the drawing properties, sensory properties and nutritional value of fermented soy milk. In order to solve the above technical problems, the present invention provides a method for preparing a fermented soy milk with strong antioxidant properties modified by bio-enzymatic hydrolysis and plant polysaccharide, wherein the fermented soy milk is obtained by inoculating thermophilic streptococcus, bifidobacterium lactis, lactobacillus acidophilus and lactobacillus plantarum in soy milk for fermentation. By combining bio-dissociation technology with plant polysaccharide and fermentation technology, the texture characteristics and nutritional value of fermented soy milk are improved, and favorable conditions are created for the actual production and industrial application of fermented soy milk.

[0005] The preparation method of the present invention is as follows:

[0006] (1) selecting clean soybeans free of impurities, peeling and removing the embryos, crushing and passing through a 180-mesh sieve, and grinding the soybeans for pretreatment, adding alkaline protease and papain to the mixed solution for enzymatic hydrolysis, and centrifuging to obtain a hydrolyzate;

[0007] (2) mixing 7S soybean protein with the hydrolyzate, adding alkaline protease thereto for secondary enzymolysis, the enzymolysis time is 2.0-2.5 hours, and then adding acidic protease for synergistic enzymolysis, the enzymolysis time is 2.0-2.5 hours;

[0008] (3) After enzymolysis, the enzymolyzed soy milk is obtained by instant sterilization, and 4.5% to 5.5% by weight of sucrose and 2.5% to 3.5% by weight of prebiotics are added to the enzymolyzed soy milk to obtain an initial mixed solution;

[0009] (4) adding 1.5% of wolfberry polysaccharide to the initial mixed solution, and homogenizing, sterilizing and cooling the initial mixed solution to obtain a soymilk mixture;

[0010] (5) adding a starter of 2.8%-3.5% by mass of thermophilic Streptococcus, Bifidobacterium lactis, Lactobacillus acidophilus and Lactobacillus plantarum to the soymilk mixture for fermentation, stirring the fermented soymilk for 5 minutes every two hours during the fermentation process, and the acidity of the fermentation is terminated at 45-50°T.

[0011] It is further defined that the refining conditions in step (1) are 3000 rpm, 40° C., 10 min, the amount of alkaline protease added is 0.05%-0.15%, the amount of papain added is 0.03%-0.1%, and the centrifugation conditions are 2000 rpm, 4° C., 15 min.

[0012] It is further defined that the mixing ratio of the 7S soybean protein and the hydrolyzate in step (2) is 1:8 (w / v).

[0013] It is further defined that the instantaneous conditions in step (3) are 135-145° C., 2-8 s, and the prebiotic is oligofructose.

[0014] It is further defined that the homogenization pressure in step (4) is 20 MPa-30 MPa, and the homogenization time is 20 min-30 min.

[0015] It is further defined that the fermentation temperature in step (5) is 40°C-43°C, and the fermentation time is 6h-10h.

[0016] Beneficial effects: The fermented soybean milk provided by the present invention is fermented by whole plants, has no beany, bitter and unpleasant smell, and the production process combines plant polysaccharides and fermentation technology through biological dissociation technology, and comprehensively utilizes the hydrolyzate of soybean water enzymatic method as an auxiliary material, which improves the texture characteristics and nutritional value of fermented soybean milk, and creates favorable conditions for the actual production and industrial application of fermented soybean milk, creating better economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the process diagram of fermentation and enzymatic hydrolysis of soy milk;

[0018] Figure 2 This is a sample picture of commercially available fermented soy milk;

[0019] Figure 3 This is a sample diagram of Example 1;

[0020] Figure 4 This is a sample diagram of Example 2;

[0021] Figure 5 The free radical scavenging rate variation diagram of commercially available fermented soy milk; wherein the horizontal axis is the fermentation time, and the vertical axis is the free radical scavenging rate;

[0022] Figure 6 This is a graph showing the free radical scavenging rate variation of fermented soybean milk in Example 1; wherein the horizontal axis is the fermentation time, and the vertical axis is the free radical scavenging rate;

[0023] Figure 7 This is a graph showing the free radical scavenging rate variation of fermented soybean milk in Example 2; wherein the horizontal axis is the fermentation time, and the vertical axis is the free radical scavenging rate; Specific embodiments

[0024] The starter cultures of Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus plantarum were purchased commercially from Shandong Zhongke Jiayi Biotechnology Company.

[0025] The soybeans selected in the present invention are Beidahuang soybeans, which are purchased commercially.

[0026] Example 1.

[0027] A method for preparing fermented drawn soybean milk with strong antioxidant properties based on bio-enzymatic hydrolysis and plant polysaccharide modification, the specific steps are as follows:

[0028] (1) Clean soybeans free of impurities are selected, peeled and germinated, crushed and passed through a 180-mesh sieve, and then subjected to a grinding pretreatment at 3000 rpm, 40° C., and 10 min. Alkaline protease and papain are added to the mixed solution for enzymatic hydrolysis, with the amount of alkaline protease added being 0.05% and the amount of papain added being 0.1%. The mixture is centrifuged at 2000 rpm, 4° C., and 15 min to obtain a hydrolyzate;

[0029] (2) 7S soybean protein was mixed with the hydrolyzate at a mixing ratio of 1:8 (w / v), alkaline protease was added thereto for secondary enzymolysis for 2.0 h, and then acidic protease was added for synergistic enzymolysis for 2.0 h;

[0030] (3) After enzymatic hydrolysis, the enzymatic hydrolyzed soybean milk is obtained by instant sterilization at 135° C. for 8 seconds, and 4.5% by mass of sucrose and 3.0% by mass of oligofructose are added to the enzymatic hydrolyzed soybean milk to obtain an initial mixed solution;

[0031] (4) Add 1.5% of Lycium barbarum polysaccharide to the initial mixed solution, homogenize the initial mixed solution, and homogenize at a pressure of 20 MPa for 30 min. After homogenization, sterilize and cool to obtain a soymilk mixture;

[0032] (5) adding 3.0% by mass of a starter culture of thermophilic Streptococcus, Bifidobacterium lactis, Lactobacillus acidophilus and Lactobacillus plantarum to the soymilk mixture for fermentation at a temperature of 40° C. for 10 h. During the fermentation process, the fermented soymilk was stirred for 5 minutes every two hours. The acidity at the end of the fermentation was 45° T.

[0033] Example 2.

[0034] A method for preparing fermented drawn soybean milk with strong antioxidant properties based on bio-enzymatic hydrolysis and plant polysaccharide modification, the specific steps are as follows:

[0035] (1) Clean soybeans free of impurities are selected, peeled and germinated, crushed and passed through a 180-mesh sieve, and then subjected to a grinding pretreatment at 3000 rpm, 40° C., and 10 min. Alkaline protease and papain are added to the mixed solution for enzymatic hydrolysis, with the amount of alkaline protease added being 0.15% and the amount of papain added being 0.03%. The mixture is centrifuged at 2000 rpm, 4° C., and 15 min to obtain a hydrolyzate;

[0036] (2) 7S soybean protein was mixed with the hydrolyzate at a mixing ratio of 1:8 (w / v), alkaline protease was added thereto for secondary enzymolysis for 2.5 h, and then acidic protease was added for synergistic enzymolysis for 2.5 h;

[0037] (3) After enzymatic hydrolysis, the enzymatic hydrolyzed soybean milk is obtained by instant sterilization at 135° C. for 8 seconds, and 5.5% by mass of sucrose and 2.7% by mass of oligofructose are added to the enzymatic hydrolyzed soybean milk to obtain an initial mixed solution;

[0038] (4) Add 1.5% of Lycium barbarum polysaccharide to the initial mixed solution, homogenize the initial mixed solution, and homogenize at a pressure of 30 MPa for 20 min. After homogenization, sterilize and cool to obtain a soymilk mixture;

[0039] (5) adding a starter of 3.3% by mass of Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus acidophilus and Lactobacillus plantarum to the soymilk mixture for fermentation at a temperature of 43° C. for 7 h. During the fermentation process, the fermented soymilk was stirred for 5 minutes every two hours. The acidity at the end of the fermentation was 49° T.

[0040] The following experiment was used to verify the experimental effect: Example 2 was used to verify the experimental effect:

[0041] 1. The indicators are determined as follows:

[0042] 1. Sensory evaluation

[0043] Ten people anonymously test the wine under bright light, looking straight ahead and evaluating the wine in terms of color, flavor, and texture. The total score of the three indicators is 100. The higher the score, the better the effect. The tasting results are statistically analyzed.

[0044] 2. Determination of antioxidant capacity

[0045] (1) Prepare DPPH solution in ethanol, then add 2 mL of sample solution (0.5 mg / mL) to 2 mL of DPPH ethanol solution. The mixture is reacted at room temperature in the dark for 30 min, and the absorbance is measured at 517 nm using a UV-visible spectrophotometer to calculate its DPPH free radical scavenging rate.

[0046] (2) Mix 7mM ABTS+ solution with 2.45mM potassium persulfate solution (2:1, V / V) and react for 12 hours at room temperature in the dark. Dilute the ABTS+ solution with distilled water until the absorbance at 734nm is 0.70±0.02 to obtain ABTS+ free radical working solution. Then, mix 0.8mL of ABTS+ free radical working solution with 200μL of sample. React at room temperature for 6min, and then transfer 200μL of the mixed solution to a 96-well plate. The absorbance of the sample is measured at 734nm using an enzyme reader, and its ABTS+ free radical scavenging rate is calculated.

[0047] (3) Prepare 0.01 mol / L ferrous sulfate, salicylic acid-ethanol, and hydrogen peroxide solutions. Add 2 mL of ferrous sulfate, salicylic acid-ethanol solution, and sample to the test tube in sequence, and then add 2 mL of hydrogen peroxide solution to start the reaction. After 30 minutes in a 37°C water bath, measure the absorbance at 510 nm and calculate to evaluate its ability to scavenge hydroxyl radicals.

[0048] 2. Results Analysis

[0049] 1. Sensory evaluation

[0050] In terms of project indicators, the color, taste and smell, texture state and overall score were evaluated. Among them, the color score of commercially available fermented soy milk was 92.9, the taste and smell score was 94.6, the texture state score was 92.8, and the overall score was 96.1; the color score of Example 1 was 94.5, the taste and smell score was 95.8, the texture state score was 94.8, and the overall score was 98.6; the color score of Example 2 was 99.3, the taste and smell score was 97.6, the texture state score was 96.9, and the overall score was 99.4.

[0051] 2. Antioxidant

[0052] In terms of antioxidant performance, commercially available fermented soy milk was compared with Example 2, and the measured indicators included DPPH clearance rate, ABTS+ clearance rate, and hydroxyl free radical clearance rate. Figure 5-7 As shown in the figure, the DPPH scavenging rates of the three groups of fermented soy milks before fermentation were 17.26%, 22.84% and 24.01% respectively. As the fermentation progressed, the DPPH free radical scavenging rate continued to increase. At the end of the fermentation, the DPPH of Example 2 reached 65.11%. The unfermented soy milk also had a certain amount of ABTS + Free radical scavenging ability. With the extension of fermentation time, the ABTS of three groups of fermented soy milk samples + The free radical scavenging ability was significantly improved. After 3h of fermentation, until the end of fermentation, the ABTS + The free radical scavenging ability increased rapidly, from 48.61% to 86.32% in Example 2; the hydroxyl radical scavenging rate in Example 2 was even better, from 18.47% at the beginning to 76.03%.

Claims

1. A method for preparing fermented soybean milk with strong antioxidant properties based on bio-enzymatic hydrolysis and plant polysaccharide modification, characterized in that: The preparation method is as follows: (1) selecting clean soybeans free of impurities, peeling and removing the embryos, crushing and passing through a 180-mesh sieve, and grinding the soybeans for pretreatment, adding alkaline protease and papain to the mixed solution for enzymatic hydrolysis, and centrifuging to obtain a hydrolyzate; (2) mixing 7S soybean protein with the hydrolyzate, adding alkaline protease thereto for secondary enzymolysis, the enzymolysis time is 2.0 to 2.5 hours, and then adding acidic protease for synergistic enzymolysis, the enzymolysis time is 2.0 to 2.5 hours; (3) After enzymolysis, sterilize the enzymolyzed soy milk to obtain an enzymolyzed soy milk, add 4.5% to 5.5% by mass of sucrose and 2.5% to 3.5% by mass of prebiotics to the enzymolyzed soy milk to obtain an initial mixed solution; (4) adding 1.5% of wolfberry polysaccharide to the initial mixed solution, and homogenizing, sterilizing and cooling the initial mixed solution to obtain a soymilk mixture; (5) adding a starter of thermophilic Streptococcus, Bifidobacterium lactis, Lactobacillus acidophilus and Lactobacillus plantarum in a mass fraction of 2.8% to 3.5% to the soymilk mixture for fermentation, stirring the fermented soymilk for 5 minutes every two hours during the fermentation process, and the acidity of the fermentation termination is 45 to 50°T.

2. The preparation method according to claim 1, characterized in that: The refining conditions of step (1) are 3000 rpm, 40° C., 10 min, the addition amount of alkaline protease is 0.05% to 0.15%, the addition amount of papain is 0.03% to 0.1%, and the centrifugation conditions are 2000 rpm, 4° C., 15 min.

3. The preparation method according to claim 1, characterized in that: In step (2), the mixing ratio of the 7S soybean protein to the hydrolyzate is 1:8 (w / v).

4. The preparation method according to claim 1, characterized in that: The instantaneous conditions in step (3) are 135-145° C., 2-8 s, and the prebiotic is oligofructose.

5. The preparation method according to claim 1, characterized in that: The homogenization pressure in step (4) is 20MPa-30MPa, and the homogenization time is 20min-30min.

6. The preparation method according to claim 1, characterized in that: The fermentation temperature in step (5) is 40°C-43°C, and the fermentation time is 6h-10h.

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